It is known that the mechanical characteristics of most synthetic materials can be improved by the inclusion of appropriate filler particles.
Trials of embedded filler particles into non-meltable polytetrafluorethylene have been made. Unexpectedly, this has resulted, due to the inclusion of the filler particles, in a reduction of essential mechanical characteristics, such as for instance tensile strength and rupture elongation. The tendency according to which the characteristics of PTFE change due to the admixture of filler substances is shown in the table hereafter:
______________________________________ PTFE .sup.+ PTFE .sup.+ PTFE .sup.+ PTFE .sup.+ Characteristics glass carbon graphite bronze ______________________________________ density x -- -- x compression strength x x x x pressure module E x x x x abrasive resistance x x x x friction coefficient x x x x temperature range O O O O dielectric strength -- -- -- -- porosity x x x x rupture strength - - - - rupture elongation - - - - yield stress - - - - elongation to yield - - - - strength tension module E - - - - fatigue strength - - - - fatigue module E - - - - ______________________________________ (Explanation of signs: x = increased; - = reduced; O = unchanged
The known low level of the mechanical strength characteristics of PTFE limits the application possibilities of this material, which in view of its chemical resistance, its excellent electric and dielectric characteristics, its antiadhesivity, its temperature resistance and its unusual antifriction properties is technically particularly interesting synthetic material when PTFE can be used at all in demanding mechanical applications, it requires in specific cases complex structural compensation for its mechanical weaknesses.
Consequently, it is an object of the present invention to allow the production of a material comprising PTFE and filler particles in such a way that the admixture of said filler particles does not cause any substantial deterioration of part of the mechanical characteristics and that the chemical, electric, antiadhesive, thermal and antifriction properties of PTFE are substantially maintained.